The earl's version of events - as told to friend Susan Maxwell-Davis before he disappeared - was that he intervened in a struggle between an unknown assailant and his wife.

Others contend he or a hired hitman intended to kill Lady Lucan but murdered Mrs Rivett by mistake.

In July 1999 the Lord Chancellor turned down the application from Lord Lucan's son, George Bingham, to take up his father's seat in the House of Lords because he couldn't provide proof that his father had died.

He was officially declared dead in October 1999 and his family was finally granted probate.

In October 2004, Scotland Yard re-opened the investigation into the murder, examining existing police evidence and using DNA profiling to try to solve the case.